Issue 4353 - Remove deprecated __proto__ syntax

lib/coreUtils.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 function desc(properties)

[Wladimir Palant, 2016/09/02 12:19:48]

Since we are only using this for inheritance, how about also exporting:

  function extend(cls, properties)
  {
    return Object.create(cls.prototype, desc(properties));
  }

This should make the callers easier to understand. I would normally suggest
handling the constructors here as well but I realized that this would degrade
performance.

[kzar, 2016/09/02 15:06:41]

Done.

 {
   let descriptor = {};
+  let keys = Object.keys(properties);
 
-  for (let key in properties)
+  for (let key of keys)
     descriptor[key] = Object.getOwnPropertyDescriptor(properties, key);

[Wladimir Palant, 2016/09/02 12:19:48]

This will fail should we ever hit a property defined on the prototype of
`properties` (Object.getOwnPropertyDescriptor returns undefined, Object.create
throws). I wonder whether the loop should be `for (let key of
Object.keys(properties))` - or maybe just check the return value of
Object.getOwnPropertyDescriptor.

[kzar, 2016/09/02 15:06:41]

Done.

 
   return descriptor;
 }
 exports.desc = desc;
+
+function extend(cls, properties)
+{
+  return Object.create(cls.prototype, desc(properties));
+}
+exports.extend = extend;